EDIT: I have added TABLE 4, now showing the effects of aid another with differing numbers of people.

I started a bit of a firestorm in my other thread when I showed math that indicated 4e's skill challenge system did not work. I realize now that I should have provided you all a great deal more data when challenging such a core mechanic. I am prepared to do that now.

I will write a description of each table beneath that table, detailing the facts I am showing. Then I will draw up some conclusions at the bottom. This post will be long.

Assumption: Party of 5 people, each has a medium skill aptitude (see below). Using medium DC at each level, COMPLEXITY: 5 challenge.

These are the skill modifiers I used as the assumption for my work. The bad collumn is a character that invests very poorly in a skill. I assumed a 14 in the stat, no skill training, and the only times he puts ability points in that skill are at 11th and 21st level.

The medium column is your standard character. I assumed a 18 stat base, +5 for skill training. The character always puts 1 of his ability bumps into that stat. The stat column shows you when he gets a bump to skill as a result of that ability bump. Other than that, there's no skill focus or items that bump his skills.

In the good column I would like to introduce Skilly McAwesome, our resident skill god. Skilly has +5 in his stat to start, +5 for training, +3 skill focus, and +2 racial. He puts points in that stat whenever he can, and he gets items to boost his skills to the maximum. I used sylvan armor from the PHB as a basis for the item column, which shows the item bonus Skilly is receiving.

A lot is going on in this table. I will go through each column.IC: Individual Check percentage. This is what percentage each character has to make the DC for that level.

PWR: Party Win Rate. How likely the party is to win the challenge at that IC.

ICMA: Individual Check Percentage with Medium Aid Another. This is the percentage if you assume that 4 people out a 5 person party are aiding that 5th person, using a skill they are medium at.

ICBA: Individual Check Percentage with Bad Aid Another. This is the same as ICMA, except in this case, each character is aiding with a skill they have a bad modifier at.

PWRBA: This is the party win rate using the ICBA. I did not do one for ICMA because the numbers would always be near 100%.

ICGS: Individual Check percentage with Good Skill. For this number, I am assuming 1 of our 5 party members is now Skilly McAwesome, and has the good skill modifier. I am then averaging the party's numbers together. IMPORTANT NOTE: Because of the averaging, the numbers I have presented will be slightly higher than actual.

PWRGS: The party win rate using the ICGS.

Table 2 CONCLUSIONS:
1) Level 7 is no man's land for doing skill challenges. The DCs and modifiers just give the party an absolute garbage chance of succeeding.
2) Without aid another, a standard party won't have better than 50% chance to make a skill challenge until high epic level.
3) With aid another using their good skills, the party's win rate flies off the chart, hitting 100% win rate extremely quickly. I didn't show the win rate for this to save space, but with the ICMA so high, its easily to see that you can't have a group aiding one person all the time, else you will autopass most skill challenges.
4) The problem continues even if you aid one person with your bad skills. These numbers quickly get to +9, and once there, you are auto succeeding on aid rolls. The numbers get magnified by this, and near 100% win rates quickly result.
Conclusion: Every person aiding 1 person in a skill challenge DOES NOT work.
5) The last two columns show our boy Skilly going to work. While he has a significant impact on his party, he does not get them to 50% PWR, in many cases not even close. However, at high levels he's working overtime, and the party has a near 100% PWR with him there.
Conclusion: The Assumption of one skill guy cannot save the system.

Table 3. -5 to our Standard DCs.
This one is for the people who are thinking about using the DC table without adding the +5 from the footnote.

Table 3 Conclusions:
1) With this system, its a ping pong match between 75% and 90% win rates until you get to higher levels in which case 100% win rate starts taking over.
2) Our boy skilly once again ramps up the rates, easily getting near 100% in very short order.

This table shows the PWR if different numbers of people are aiding each round. The assumption is people are aiding with their medium skills. The first is no aid, the second 1 person is aiding, then 2 and then finally 3 people aiding. The effects of 4 people aiding are provided in table 2.Table 4 Conclusions:

1) The big thing to note is where is the massive jump between 2 people and 3 people aiding.

Final Conclusions:
1) Aid another does not fix the system. In many cases, it causes an overload effect, ramping up the party to 100% win rates.
2) The system has a trouble tolerating a skill guy in the party, and can quickly get the party up to 100% win rates.
3) The system is very sensitive to variation. Even the slightest change in the parties skills can have a strong impact on the system.
4) Epic DCs are too low.
5) -5 to DCs does help, but it does not fix the problem.

I hope this data will give you a wider view of the skill challenge problem. If you believe the system is broken and would like a solution, I have already constructed a much stronger, numerically tighter system that addresses most of the big problems...and I'm currently working on making it better. You can find that here: http://www.enworld.org/showthread.php?t=229796

I agree that the skill challenge system has some issues that would cause problems for an inexperienced DM. I feel that more veteran DMs would "adjust on the fly" to make the system more appropriate during play.

The question I have about all of this is what happened during the playtest phase? Has there been any official statement or clarification from WotC about the skill challenge system?

I have a hard time believing that this made it through playtest unless there is something either erroneously added to, or left out of, the rules.

Bravo, Stalker0. Thank you for doing all of this math. My group knew the system was broken the first time we played it. I think this math makes it clear that even when steps are taken to make the system playable, such as with Aid Another or lowering the DCs by 5, it still leaves a highly flawed system that does not provide a good, easily scaled tool for the DM to challenge his party.

I still can't fathom how this made it into the final books.

I do have one question, though. Let's say that the DC table is totally wrong, shouldn't have been in the books at all, and there's a different, totally differently balanced table. I know you've lowered the variance in your version, but is there hope for the system with a better table of DCs? I'm really just thinking aloud here, wondering if that was where the mistake was made.

I don't really have a problem with Skilly McAwesome always or almost always winning skill challenges related to his own skill. But the aid another thing is a good demonstration. Seems like if they are going to have skill checks scale with level, they need to have the aid another DC scale with level too.

So skill challenges actually have the opposite problem to the one you initially claimed? In other words, instead of being nigh-impossible, they're near-autosuccesses now?

It's only broken in that direction if aid another is allowed in the challenge without limitation, which seems unlikely given that many of the sample challenges have skill uses that are similar to aid another (in that they give a +2 to someone else using one skill in the challenge) but have vastly higher DC than Aid Another does, so you would essentially be penalised for using those options instead of using Aid Another (to see some examples, check Urban Chase and Lost in the Wilderness. Both allow Perception to give a +2 for an Easy check, which is always harder than an Aid Another).

Also, I think one of his main points since the beginning was that the system was not very tolerant to minor changes in the PCs' favour and quickly goes off the charts with high success rates, which this reinforces.

It's only broken in that direction if aid another is allowed in the challenge without limitation, which seems unlikely given that many of the sample challenges have skill uses that are similar to aid another (in that they give a +2 to someone else using one skill in the challenge) but have vastly higher DC than Aid Another does, so you would essentially be penalised for using those options instead of using Aid Another.

I wonder if this is because we're comparing optimum and err... antioptimum(?)... circumstances, though? Most of the time neither case will apply; it'll be somewhere in between. And where optimum circumstances exist, I guess it should be easy.

I'm not dedicated anoutgh to analyse the tables above; however Mr. Skilly McSkill won't get to use his optimum skill on ALL five of the rolls. There's gonna be a range in there; perhaphs two people will have veery high skills they can use, another couple will have medium skills and the last with crappy skills in this particular instance (although in a different skill challenge he might rival Skilly's scores in the first challenge).

Aid Another is going to vary from 0 to 4 uses in a particular skill check by a 5-man party.

I comes across to me as a lot of sliding variables which are all being set at 0 together, or all being set at 10 together; this probably isn't a situation that's likely to occur.

PWR is what he originally worked with. As you can see, you don't win until late epic with anything approaching regularity.

PWRBA is what happens if you let aid anothers be used. You usually win, latter on you always win.

PWEGS is what happens if you don't aid another, but you have someone in the party who is amazingly good at the skill in question. Numbers are ALL over the place, another thing mentioned in the earlier analysis.

The next table is what happens if you lower all DCs by 5. Crazyness happens.

All this data shows that the skill challenge system, as currently written, is crap. It's a sad day. Hopefully WotC throws Stalker0 on the payroll, as he seems willing to work on fixing it =P